The invention relates to an oil injected screw compressor that oil is injected into its compression chamber at the time of cooling compression heat generated in the main body of the compressor.
In an oil injected screw compressor in the related art, for example, as described in JP-A-63-106394, compressed air that is discharged from the main body of the compressor and contains oil is introduced into a container called an oil separator through piping. Moreover, another example of the oil injected screw compressor is disclosed in JP-A-60-216092. In the oil injected screw compressor disclosed in JP-A-60-216092, the main body of a compressor is built in an oil separator.
In the oil injected screw compressor disclosed in JP-A-63-106394, the oil separator is provided separately from the main body of a compressor, so piping for connecting the oil separator to the main body of the compressor is required, which makes it difficult to reduce the size of the compressor. On the other hand, in the oil injected screw compressor which is disclosed in JP-A-60-216092 and whose main body is built in the oil separator, in order to separate oil effectively by an oil separating element provided in the oil separator, the distance between the oil separating element and the surface of oil needs to be made large. As a result, the oil separator is made large in diameter to make it difficult to reduce the size of the oil injected screw compressor. In addition, the oil injected screw compressor disclosed in this publication needs to have oil in the oil separator drained when the main body of the compressor is overhauled, so that it is inadequate with respect to maintenance.